Thulium holmium-doped fiber laser mode-locked using Sb2Te3 saturable absorber coated arc-shaped fiber

Abstract

In this study, the topological insulator (TI) antimony telluride (Sb2Te3) was used as a saturable absorber (SA) to obtain stable mode-locked pulses in a thulium holmium-doped fiber laser (THDFL). A liquid-phase exfoliation (LPE) approach was used to obtain the SA material without chemicals or surfactants. The SA device was prepared by drop-casting the material onto the arc-shaped fiber for integration into the 2.0 µm laser cavity. The prepared device also exhibits nonlinear absorption properties with normalized modulation depth, saturation intensity, and non-saturable loss of 36.16 %, 0.046 MW/cm2, and 63.84 %, respectively. Furthermore, stable mode-locked pulses were readily obtained at a pump power of 307.60 mW, where the center wavelength of the laser was recorded to be 1902.06 nm with a full width at half maximum of 2.88 nm. The pulses had a repetition rate of 10.88 MHz and pulse width of 1.32 ps with a signal-to-noise ratio (SNR) value of about 61.21 dB. The results show that Sb2Te3 SA demonstrated excellent performance and can be further explored for future photonics applications.